Air gap type microscope objective

ABSTRACT

A six member microscope objective having a numerical aperture of substantially 0.90 and a magnification of substantially 100x for use without oil is disclosed.

BACKGROUND OF THE INVENTION

This invention relates to improvements in a microscope objective, and in particular to a semi-apochromatic microscope objective with a numerical aperture of substantially 0.90, a magnification of substantially 100×, and a clear working distance of substantially 0.3 millimeters.

It is the object of this invention to provide such a microscope objective in which the usual chromatic image aberrations are exceptionally well corrected, as well as spherical aberration, coma, and astigmatism, while having a substantially flat image over a 20 millimeter field when used with telescope objective as described in U.S. Pat. No. 3,355,234 and a typical 10× eyepiece.

THE DRAWING

The drawing is an optical diagram of an embodiment of the present invention.

THE DESCRIPTION

Referring now to the drawing, the numeral X designates the objective in general, and aligned components of the objective. Component I is a concavo-convex positive singlet. Rearward of component I is component II, a concavo-convex positive doublet, followed respectively by component III, a double-convex positive doublet, component IV, a concavo-convex negative doublet, component V, a convex-concavo positive doublet and component VI, a double-concave negative doublet.

Table I sets forth the lens parameters of the scope of the invention. The axial thicknesses of successive lens elements are designated T₁ to T₁₁ and the successive axial spaces from object plane O are S₁ to S₆. The successive lens radii are designated R₁ to R₁₇ where the minus sign (-) applies to surfaces whose center of curvature lies on the object side of their vertices. The refractive indices and Abbe numbers of the glasses in the successive lenses are designated ND₁ to ND₁₁, and ≧₁ to≧₁₁ respectively.

                                      TABLE I                                      __________________________________________________________________________                               Refractive                                                                               Abbe                                          Radius  Thickness                                                                             Space   Index     Number                                     Lens                                                                              (R)     (T)    (S)     (ND)      (ν)                                     __________________________________________________________________________                       S.sub.1 = 0.268 f                                               R.sub.1 = -0.909 f                                                          I          T.sub.1 = 0.992 f                                                                             1.77< ND.sub.1 <1.79                                                                     35<ν.sub.1 <40                             R.sub.2 = -0.928 f                                                                            S.sub.2 = -0.027 f                                              R.sub.3 = 84.089 f                                                                     T.sub.2 = 0.301 f                                                                             1.59< ND.sub.2 < 1.62                                                                    53<ν.sub.2 <60                          II R.sub.4 = 2.593 f                                                                      T.sub.3 = 1.831 f                                                                             1.41< ND.sub.3 < 1.44                                                                    92<ν.sub.3 <97                             R.sub.5 = -2.475 f                                                                            S.sub.3 = 0.164 f                                               R.sub.6 = 2.843 f                                                                      T.sub.4 = 0.603 f                                                                             1.75< ND.sub.4  <1.77                                                                    25<ν.sub.4 <30                          III                                                                               R.sub.7 = 2.077 f                                                                      T.sub.5 = 2.193 f                                                                             1.41< ND.sub.5 <1.44                                                                     92<ν.sub.5 <97                             R.sub.8 = -6.192 f                                                                            S.sub.4 = 0.537 f                                               R.sub.9 = -63.159                                                                      T.sub.6 = 0.548 f                                                                             1.77< ND.sub.6 <1.79                                                                     35<ν.sub.6 <40                          IV R.sub.10 = 2.149 f                                                                     T.sub.7 = 1.918 f                                                                             1.41< ND.sub.7 <1.44                                                                     92<ν.sub.7 <97                             R.sub.11 = -3.256 f                                                                           S.sub.5 = 0.054 f                                               R.sub.12 = 3.942 f                                                                     T.sub.8 = 0.548 f                                                                             1.68< ND.sub.8 <1.71                                                                     28<ν.sub.8 <34                          V  R.sub.13 = 2.522 f                                                                     T.sub.9 = 1.809 f                                                                             1.70< ND.sub.9 <1.74                                                                     35<ν.sub.9 <40                             R.sub.14 = 6.524 f                                                                            S.sub.6 = 0.751 f                                               R.sub.15 = -2.741 f                                                                    T.sub.10 = 2.193 f                                                                            1.77< ND.sub.10 <1.79                                                                    24<ν.sub.10 <29                         VI R.sub.16 = -2.077                                                                      T.sub.11 = 1.096 f                                                                            1.61< ND .sub.11 <1.64                                                                   55<ν.sub.11 <60                            R.sub.17 = 10.344 f                                                         __________________________________________________________________________

The indices and Abbe numbers are absolute values and f has a value between 1.75 and 2.00 mm.

Numerically stated, the constructional data for one successful form of the invention is given below where f=1.82395 mm.

                                      TABLE II                                     __________________________________________________________________________                             Refractive                                                                              Abbe                                             Radius  Thickness                                                                             Space Index    Number                                        Lens                                                                              (R)     (T)    (S)   (ND)     (ν)                                        __________________________________________________________________________                       S.sub.1 = 0.49                                                  R.sub.1 = -1.659                                                            I          T.sub.1 = 1.81                                                                              ND.sub.1 = 1.781607                                                                     ν.sub.1 = 37.08                               R.sub.2 = -1.693                                                                              S.sub.2 = 0.05                                                  R.sub.3 = -153.375                                                                     T.sub.2 = 0.55                                                                              ND.sub.2 = 1.607286                                                                     ν.sub.2 = 56.65                            II R.sub.4 = 4.73                                                                         T.sub.3 = 3.34                                                                              ND.sub.3 = 1.433843                                                                     ν.sub.3 = 95.60                               R.sub.5 = -4.515                                                                              S.sub.3 = 0.3                                                   R.sub.6 = 5.187                                                                        T.sub.4 = 1.1                                                                               ND.sub.4 = 1.761555                                                                     ν.sub.4 = 27.10                            III                                                                               R.sub.7 = 3.79                                                                         T.sub.5 = 4.0                                                                               ND.sub.5 = 1.433843                                                                     ν.sub.5 = 95.60                               R.sub.8 = -11.295                                                                             S.sub.4 = 0.98                                                  R.sub.9 = -115.2                                                                       T.sub.6 = 1.0                                                                               ND.sub.6 = 1.781607                                                                     ν.sub.6 = 37.08                            IV R.sub.10 = 3.92                                                                        T.sub.7 = 3.5                                                                               ND.sub.7 = 1.433843                                                                     ν.sub.7 = 95.60                               R.sub.11 = -5.94                                                                              S.sub.5 = 0.1                                                   R.sub.12 = 7.19                                                                        T.sub.8 = 1.0                                                                               ND.sub.8 = 1.698749                                                                     ν.sub.8 = 30.06                            V  R.sub.13 = 4.6                                                                         T.sub.9 = 3.3                                                                               ND.sub.9 = 1.723254                                                                     ν.sub.9 = 37.94                               R.sub.14 = 11.9                                                                               S.sub.6 = 1.37                                                  R.sub.15 = - 5.0                                                                       T.sub.10 = 4.0                                                                              ND.sub.10 = 1.784443                                                                    ν.sub.10 = 26.21                           VI R.sub.16 = -3.79                                                                       T.sub.11 = 2.0                                                                              ND.sub.11 = 1.622896                                                                    ν.sub.11 = 58.13                              R.sub.17 = 18.867                                                           __________________________________________________________________________ 

What is claimed is:
 1. A semi-apochromatic air gap microscope objective having a magnification of substantially 100× and a numerical aperture of substantially 0.90 for forming an image of an object plane, said image being well corrected for spherical and chromatic aberrations, coma, astigmatism and curvature of image field, said objective comprising:a front concavo-convex positive singlet lens component I; a second concavo-convex positive doublet lens component II; a third double-convex positive doublet lens component III; a fourth concavo-convex negative doublet lens component IV; a fifth convex-concavo positive doublet lens component V; and a sixth double-concave negative doublet lens component VI;all of said lens components being axially aligned.
 2. The objective of claim 1 having the following lens parameters where a minus sign (-) designates a surface curvature having a vertex on the object side of the surface, wherein f is between 1.75 and 2.00 mm, and

                                      TABLE I                                      __________________________________________________________________________                               Refractive                                                                               Abbe                                          Radius  Thickness                                                                             Space   Index     Number                                     Lens                                                                              (R)     (T)    (S)     (ND)      (ν)                                     __________________________________________________________________________                       S.sub.1 = 0.268 f                                               R.sub.1 = -0.909 f                                                          I          T.sub.1 = 0.992 f                                                                             1.77< ND.sub.1 <1.79                                                                     35<ν.sub.1 <40                             R.sub.2 = -0.928 f                                                                            S.sub.2 = -0.027 f                                              R.sub.3 = 84.089 f                                                                     T.sub.2 = 0.301 f                                                                             1.59< ND.sub.2 < 1.62                                                                    53<ν.sub.2 <60                          II R.sub.4 = 2.593 f                                                                      T.sub.3 = 1.831 f                                                                             1.41< ND.sub.3 < 1.44                                                                    92<ν.sub.3 <97                             R.sub.5 = -2.475 f                                                                            S.sub.3 = 0.164 f                                               R.sub.6 = 2.843 f                                                                      T.sub.4 = 0.603 f                                                                             1.75< ND.sub.4  <1.77                                                                    25<ν.sub.4 <30                          III                                                                               R.sub.7 = 2.077 f                                                                      T.sub.5 = 2.193 f                                                                             1.41< ND.sub.5 <1.44                                                                     92<ν.sub.5 <97                             R.sub.8 = -6.192 f                                                                            S.sub.4 = 0.537 f                                               R.sub.9 = -63.159                                                                      T.sub.6 = 0.548 f                                                                             1.77< ND.sub.6 <1.79                                                                     35<ν.sub.6 <40                          IV R.sub.10 = 2.149 f                                                                     T.sub.7 = 1.918 f                                                                             1.41< ND.sub.7 <1.44                                                                     92<ν.sub.7 <97                             R.sub.11 = -3.256 f                                                                           S.sub.5 = 0.054 f                                               R.sub.12 = 3.942 f                                                                     T.sub.8 = 0.548 f                                                                             1.68< ND.sub.8 <1.71                                                                     28<ν.sub.8 <34                          V  R.sub.13 = 2.522 f                                                                     T.sub.9 = 1.809 f                                                                             1.70< ND.sub.9 <1.74                                                                     35<ν.sub.9 <40                             R.sub.14 = 6.524 f                                                                            S.sub.6 = 0.751 f                                               R.sub.15 = -2.741 f                                                                    T.sub.10 = 2.193 f                                                                            1.77< ND.sub.10 <1.79                                                                    24<ν.sub.10 <29                         VI R.sub.16 = -2.077                                                                      T.sub.11 = 1.096 f                                                                            1.61< ND .sub.11 <1.64                                                                   55<ν.sub.11 <60                            R.sub.17 = 10.344 f                                                         __________________________________________________________________________


3. The objective of claim 2 having the following lens parameters where a minus sign (-) designates a surface curvature having a vertex on the object side of the surface, wherein f is between 1.75 and 2.00 mm, and

                                      TABLE II                                     __________________________________________________________________________                             Refractive                                                                              Abbe                                             Radius  Thickness                                                                             Space Index    Number                                        Lens                                                                              (R)     (T)    (S)   (ND)     (ν)                                        __________________________________________________________________________                       S.sub.1 = 0.49                                                  R.sub.1 = -1.659                                                            I          T.sub.1 = 1.81                                                                              ND.sub.1 = 1.781607                                                                     ν.sub.1 = 37.08                               R.sub.2 = -1.693                                                                              S.sub.2 = 0.05                                                  R.sub.3 = -153.375                                                                     T.sub.2 = 0.55                                                                              ND.sub.2 = 1.607286                                                                     ν.sub.2 = 56.65                            II R.sub.4 = 4.73                                                                         T.sub.3 = 3.34                                                                              ND.sub.3 = 1.433843                                                                     ν.sub.3 = 95.60                               R.sub.5 = -4.515                                                                              S.sub.3 = 0.3                                                   R.sub.6 = 5.187                                                                        T.sub.4 = 1.1                                                                               ND.sub.4 = 1.761555                                                                     ν.sub.4 = 27.10                            III                                                                               R.sub.7 = 3.79                                                                         T.sub.5 = 4.0                                                                               ND.sub.5 = 1.433843                                                                     ν.sub.5 = 95.60                               R.sub.8 = -11.295                                                                             S.sub.4 = 0.98                                                  R.sub.9 = -115.2                                                                       T.sub.6 = 1.0                                                                               ND.sub.6 = 1.781607                                                                     ν.sub.6 = 37.08                            IV R.sub.10 = 3.92                                                                        T.sub.7 = 3.5                                                                               ND.sub.7 = 1.433843                                                                     ν.sub.7 = 95.60                               R.sub.11 = -5.94                                                                              S.sub.5 = 0.1                                                   R.sub.12 = 7.19                                                                        T.sub.8 = 1.0                                                                               ND.sub.8 = 1.698749                                                                     ν.sub.8 = 30.06                            V  R.sub.13 = 4.6                                                                         T.sub.9 = 3.3                                                                               ND.sub.9 = 1.723254                                                                     ν.sub.9 = 37.94                               R.sub.14 = 11.9                                                                               S.sub.6 = 1.37                                                  R.sub.15 = - 5.0                                                                       T.sub.10 = 4.0                                                                              ND.sub.10 = 1.784443                                                                    ν.sub.10 = 26.21                           VI R.sub.16 = -3.79                                                                       T.sub.11 = 2.0                                                                              ND.sub.11 = 1.622896                                                                    ν.sub.11 = 58.13                              R.sub.17 = 18.867                                                           __________________________________________________________________________ 